Ice maker



May 1956 v. G. DRL-:1ER 2,743,588

l ICE MAKER 2 Sheets-Sheet. l

Filed March 5, 1953 ATTORNEY May 1, 1956 v. G. DRL-:IER 2,743,588

ICE MAKER Filed March 5, 1955 2 Sham-5-511981 2 United States Patent O ICE MAKER Victor G. Dreier, Evansville, Ind., assigner to flervcl, Inc., New York, N. Y., a corporation of Deiaware Application March 5, 1953, Serial No. 340,447

11 Claims. (Cl. SZ-7) This invention relates to automatic ice makers, and particularly a method of and means for heating an ice mold so as to break the bond between the mold surfaces and the ice particles frozen therein.

More particularly, this invention relates to the utilization of waste heat from a refrigerating system to thaw ice cubes free of a mold in an automatic ice maker.

For purpose of illustration, I have incorporated my invention in an automatic ice maker like that disclosed and claimed in a copending patent application of Harry C. Shagaloff, Serial No. 325,097, tiled December 10, 1952, now Patent No. 2,717,498, granted September 13, 1955.

Brieiiy, the above Shagaloff application discloses an automatic ice maker wherein an ice mold and an ejector mechanism are located Within the low temperature or freezing compartment of a household refrigerator. ice mold is divided into ice forming compartments, each having a generally arcuate contour so that the ejector mechanism, which is mounted above the mold, may ro tate through the ice forming compartments of the mold and sweep the ice pieces therefrom. The ice pieces are thawed free of the mold by an electric heating element that is embedded in the bottom of the mold. The ice removing action is automatic, as is the filling of the mold, freezing, and loosening of the ice pieces. The ice pieces are detained on the ejector mechanism for thorough drying before discharged to storage. The automatic operation is stopped short of discharge of ice to storage and remains suspended during the time that a desired quantity of ice is held in storage. Power for operating the ejector mechanism and the control mechanism therefor is provided by a geared electric motor. This motor is of 4the type that will stall while energized when the ejector mechanism contacts the ice frozen solidly in the mold, without burning out or otherwise harming the motor.

The electric motor and the measuring vessel for supplying f a measured quantity of water to the ice mold are located on the rear exterior wall of the refrigerator. The measuring vessel is of an expansible diaphragm type wherein, when an inlet water valve is open, water under line pressure Hows into the vessel and expands the diaphragm. Then, when the inlet valve is closed and an outlet valve opened, the diaphragm contracts and forces the measured quantity of water to the ice mold.

It is an object of this invention to provide an improved means for breaking the frozen bond between an ice mold and ice pieces frozen therein.

It is a further .object of this invention to utilize waste heat from the refrigerating system that freezes water in an ice mold for thawing the ice free of the mold.

Itis a further and more specific object or" this invention to utilize the same mechanism that is used for measuring and conveying water to an ice mold to be frozen, for conveying a heated fluid to the exterior of the ice mold compartments for thawing the ice free of such compartments.

Briefly, in accordance with this invention, I provide an ice mold having a heating fluid jacket or `fluid tight The "ice

compartment around all sides, except the open top, of the ice-forming compartments. A water measuring vessel is provided with a flexible-expansible diaphragm therein and is constructed in a manner that the diaphragm divides the vessel into two compartments. One of such compartments contains a measured quantity of water when the diaphragm is expanded, which water is conveyed to the mold for freezing when the diaphragm is contracted. The other compartment contains a measured quantity of a heating iiuid when the diaphragm is contracted, which iluid is conveyed to the jacket around the exterior of the ice mold to free the ice pieces therefrom, when the diaphragm is expanded. The heating iiuid may be any suitable liquid that has a relatively low freezing point, a relatively high boiling point and is not obnoxious to foodstuffs or the like that may be placed in the refrigerator. An ethylene gycol solution has been found an excellent liquid for this purpose.

In the specific illustration shown in the drawings, the portion of the measuringvessel that contains the heating iluid is placed in good thermal contact with the rectiiier of an absorption refrigerating system that is used to freeze the ice in the mold. If desired, this portion of the measuring vessel may be placed in thermal contact with the condenser of the refrigerating system, or it may be arranged to be heated by the products of combuston from the generator of such refrigerating system. Also, when used with a compression type refrigerating system, the portion of the measuring vessel that contains the heating tluid may be placed in thermal contact with the condenser or other heat dissipating part of such refrigerating system.

In accordance with this invention, heat from the refrigerating system, that Would otherwise be wasted, is used to free the ice pieces from the mold, and the utilization of this waste heat improves the operating efficiency of such refrigerating system. Also, the heated fluid is distributed around the exterior of the ice forming compartments of the mold in a manner that the ice forming surfaces are quickly and uniformly heated. This results in a saving of ice and also prevents excess water, from the thawing of the ice, from collecting in the mold compartments. Otherwise, should excess thawing water co1- lect in the ice forming compartments, it may result in an overflowing of the mold compartments when the measured quantity of water is conveyed thereto with the next ice making cycle.

The above and other objects and advantages of this invention are set forth in more technical detail in the following description and accompanying drawings where- Fig. l is a schematic illustration of an automatic iceV maker and an absorption refrigerating system utilizing this invention;

Fig. 2 is a schematic `illustration of the automatic ice maker and a wiring diagram of the controls for such ice maker;

Fig. 3 is a transverse section through the ice mold and showing a batch of ice being thawed free of the mold;

Fig. 4 is a transverse vertical section similar to Fig. 3 and showing one batch of ice being dried on the ejector' mechanism while a second batch is being frozen in the mold;

Fig. 5 is a schematic illustration of a modified wate measuring mold and heating mechanism.

Refrigeratng system In Fig. l of the drawing, I have illustrated my inven tion embodied in an absorption refrigerating system of the unipressure type. A system of this type includes a generator 10, a rectifier 11, a condenser 12, an evaporator 13, a gas heat exchanger 14, an absorber 15 and a liquid heat exchanger 16, all interconnected in a manner well rial is attached to the front end of the mold by a plurality of screws, not shown. The rear ice forming compartment of the mold is closed by `a combined closure member and mounting plate 71 that is formed of plastic or other thermal and electrical insulating material. A copper heat transfer plug is imbedded in the plastic closure member 71, with the front surface thereof in contact with water in the rear compartment of the mold. The plastic closure memberand the copper plug each have an opening or well extending transversely therethrough to receive the bulb or temperature sensing element 72a of a mold thermostat 72, which `bulb is placed in goodv thermal contact with the copper insert. A compartment is provided in the rear of theplastic closure member 71 and has located therein a thermostat reset heater 73, which also is in thermal contact with the copper insert. The compartment in the rear closure member is closed by an insulating plate that is held in position by a plurality of. screws, not shown. The plastic closure member 71 is provided with a boss 74 having a downwardly and inwardly inclined opening therethrough `for the reception of a water tube 75. It has been found that the insulating p effect of the plastic closure member 71 may prevent the thermostat bulb 72a from resetting the thermostat 72 by the time the cubes are loosened. Therefore, some heat is supplied directly to the copper insert and from there to the thermostat bulb during an ice release cycle by the thermostat reset heater 73. Only so much of the end closure member, the copper plug and the reset heater, as is necessary for a complete understanding of this invention are illustrated and described herein. For a detailed description of these elements reference may be had to the copending application of Harry C. Shagalotf, Serial No. 325,097, referred to above. l

Ejector mechanism The ejector mechanism includes a shaft 80 mounted for clockwise rotation at its front end in the front mounting plate 70 and at its rear end in the closure member 71. This shaft has a flat portion 81 on the upper part thereof, and is provided with a plurality of ejector blades 82, one for each ice mold compartment, at one side of the shaft. As shown in Figs. 3 and 4, the ejector shaft is mounted off center relative to the longitudinal axis of the mold and the blades 82 are at an angle to the dat portion 81 of the shaft. An electric motor 83, for driving the ejector shaft S0, is mounted in any suitable manner on the rear wall of the refrigerator, and is connected to the rear of the ejector shaft by a universal coupling, not shown. This electric motor is geared down from 3400 R. P. M. to approximately 2 R. P. M. and is of a type motor that stalls while energized `when the ejector blades initially contact the ice frozen solid in the mold. An electric motor of this type is disclosed and claimed in a copending patent application of Sven W. E. Andersson, Serial No. 325,145, tiled December 10, 1952, now Patent No. 2,717,501, granted September 13, 1955.

Stop switch A stop switch 85 comprises a channel member 86 that is generally L-shaped in plan and is connected by a pivot pin, not shown, to the upper right side of the rear clo sure member 71. A vane 87 made of a thermal and elec trical insulating material is attached to the longitudinal portion of the channel member and projects downwardly therefrom. The channel member is adapted to be contacted by a cam member 88 mounted upon the ejector shaft 80. The cam 88 is so shaped that upon rotation of the ejector shaft the cam contacts the channel member and gradually raises it to a substantially horizontal position. Then the cam draws away and permits the channel member to fall by gravity to its normal position shown in Fig. 2. A mercury switch 89 is mounted on the transverse portion of the channel member in a manner that when the channel member is in the position shown in Mold lling and ice thawing mechanism Referring to Figs. 1 and 2, the structure for filling the l ice mold 22 with a measured quantity of water includes the measuring vessel 50 connected to a suitable supply of water by a conduit 90 having an inlet valve 92 therein. The conduit 90 has a T-connection and a conduit 91 leading to an outlet valve 93, which outlet valve has the conduit 75' leading therefrom to the ice mold 22. The measuring vessel 50 is attached to the rear wall of the refrigerator in any suitable manner and is formed of an aluminum casting having an upper portion of generally hemispherical shape with an outwardly projecting flange 96 at the upper' end thereof, and a lower portion 97 of cylindrical shape ared at the bottom and having a sleeve or guide member 9S projecting upwardly from the lower portion thereof into the bottom of the hemispherical portion. As stated above, the flared portion. of the measuring vessel is placed in good thermal contact with the rectifier 11. A cover plate 99 made of copper or other suitable material is attached to the open end of the measuring chamber by a plurality of set screws 100.

A liexible rubber diaphragm 101 is fitted within the hemispherical portion of the measuring vessel and is secured therein by a peripheral liange portion 102 located between the `llange 96 of the measuring vessel and the marginal edge of the cover plate 99. A piston, having a stem 103 slidably mounted in the sleeve 98 and a head 10d which contacts the undersurface of the flexible diaphragm 101, is located in the lower portion of the measuring vessel. A compression spring 105 is located between the undersurface of the piston head and the lower inner surface of the cylindrical portion of the measuring vessel. A bypass or drain opening 106 is provided in the lower end of the sleeve 98. In the extended position of the diaphragm 101, as shown in Fig. 2, the hemispherical portion of the measuring vessel contains a measured quantity of water to be conveyed to the ice forming compartments of the mold 22. Whereas, in. the contracted position of the diaphragm as shown in Fig. 1, the measuring vessel contains the heating fluid that is later conveyed to the compartment 66 around the ice forming compartmetns for thawing the ice pieces therefrom. The capacity of the measuring vessel with the diaphragm eX- panded, as shown in Fig. 2, is such as to fill the iceforming compartments of the mold with water to the proper level, as shown in Fig. 4, and the capacity of the measuring vessel with the diaphragm contracted, as shown in Fig. l, is such as to lill the compartment 66 with heat-i ing iiuid to the proper level, as shown in Fig. 3.

Modified mold filling and ice thawingl mechanism A second embodiment of this invention is illustrated in Fig. 5. Here the water measuring device is of the type illustrated and described in a copending patent application of Sven W. E. Andersson, Serial No. 205,519, filed January 1l, 1951, now Patent No. 2,717,495, granted September 13, 1955, wherein the water measuring cylinder also supplies power for operating the ice ejector mechanisrn. Only so much of the water measuring device as s necessary for a complete understanding of this invention is illustrated and described here. For a detailed description of a combined water measuring and power mechanism of this type reference may be had to the above Andersson application.

Referring now to Fig. 5, reference numeral 50 indi cates generally a water measuring, power supplying and iluid heating device which includes a cylinder 97 closed at the top and bottom, and having the bottom in good thermal contact with a rectifier 11 of an. absorption refrigerating system. A piston 104', provided with a piston rod 103', divides the cylinder into an upper water ananas,

measuring chamber and a lower heating fluid chamber. A water conduit 90.', having `inlet and outletv valves. there in not shown, connectsthe upper chamber to a source of water supply and to the freezing compartments of an ice mold. A heating uid conduit 51 connects the lower Chamber ot the cylinder with the heating fluid compartment of the ice mold. The piston rod 103' has a ilexible cable 14.0 connected thereto, at one end with theA opposite end thereof connected to a return spring 142. The flexible. cableA 140 rotates a ratchet and pulley mechanism 143 and is guided by an. idle pulley 144. An ejector shaft 80..is rotated one revolution in a given direction with each downward stroke of the piston 104.

vWith the inlet valve, inA the Water line 90. open, water flows into the, cylinder 97 and forces the piston 104 and attached piston rod 103, downward, thereby forcing 'the heating. fluid from the bottom of the, cylinder through conduitV S1. to the beating ,compartment of the ice mold. The downward movement of the piston rod and attached cable'140 rotates the ratchet and p ulley mechanism 143 and, the ejector shaft which ejects the ice pieces from the, mold. Then the positionsl of the inlet and outlet valves are reversed and, the return spring 142 contracts and draws the piston. rod and attached piston upward in the cylinder, which discharges the measured quantity of water through conduit to the icel forming compartments of the mold, and the heating duid ows by gravity from the heating compartment of the mold, through conduit 51 back to the measuring cylinder. The heating fluidv contained in the measuring cylinder 97 is heated by therectitier 11 during the next freezing cycle of operation of the ice mold. lf desired, the measuring vessel 50 of Fig. 5. may be used in place of thel measuring vessel 50 ofl Figs. l and 2, in which case the ratchet and pulley mechanism 143 would be eliminated, since the ejector mechanism of Figs. l and 2.is driven bythe electric motor 83.

Ice maker controls Referring to Fig. 2, L1 and L2 are the two sides of a 115 volt A. C. electric supply circuit. 110 is a double pole double throw manually operated switch, shown in the on position to operate the ice maker. In the ott position the lower blade lltla of switch will be at terminal 11-1, which is dead, and the upper blade 1110b will be at terminal 112, which keeps the generator burner-47 operating under the control of the thermokstat 58. Thus, in the olf position of switch 110, all circuits to they ice maker are broken, but the refrigerator continues'to operate under the inuence of the thermostat 58. Normally, current is fed to the ice maker from L1 through switch blade 11.011, connecting link 110e, switch blade 110e and through a terminal 113 ofswitch 110. lf stop switch 35 is open, indicating'that the storage receptacle 114 is full of ice cubes, the ice maker stands idle. If the stop switch is closed, as positioned in Fig. 2, nothing happensuntill the moldthermostat 72 snapsV avswitch 115V to a terminal 116 indicating that the water in the ice mold 22 has been completely frozen into ice.

A, double pole double throw push button switch operated automatically by the refrigerator doory (not shown) is'indicated generally by numeral 117 and is shown in the closed door'position. In the open door position,.the upper blade 117:1 ofv switch 117 'snaps-from, terminal 118 totermin'al119, which is deadand the lower blade-117b snaps to terminal 120, to energize a light 121 within theu refrigerator. Thus, the ice maker cannot run'while the refrigerator door is open. With the refrigerator door closed, the interior light 121 is deenergized and the ejector motor 83 is energized.

The.starting position of the ejector shaft 30 is the position it has when water is being frozen in the mold 22, andthe previous batch of ice cubes is resting on the ejector-3` blades 82; as shownin Fig. 4. When the water is completely frozento ice in the mold',`the mold thermostat 72y snaps the switch 115 -to terminal 116 energizing the ejector motor-83. Tlnisi .the ejector motor begins, to rotate, andthe" dried iee.pieces are. discharged from,r the ejectorbladesinto y thestorage receptacle 114 that is lo cated beneath the mold; -At about the 45 pointof rotation the 'water-.outletvalve 93 which stands open dur ing thepfreezing cycle'is. closed. When the ejector motor has rotatedfthe` shaft 8,0 and` attached blades 82 about 60 'from thestartingpositiona cam. 122 on the ejectorshaft, 8.0. snapsY a micro. switch 126 from the terminalv 12710. terminal 1.28. This deenergizes and closesr the solenoid valve 5.7 infuel gas line and energizes the thermostat reset heater .73. ".At about. the point of rotation of the. ejectorjmotor, the water inlet valve `92 is opened. by a cam 13,0 on .the ejector shaft and water begins to. ow. fromthesource of supply into. the measuring vesseLSl..v v t As the water, ilowsinto the measuring vessel, the ilex-4 ihle. diaphragm 101, isiexpandedfrom the positionshown in Fig. .l `to.thatshown in*y Eig.; 2; whereupon, the. heating, lluid containediinthe measuring vessel below theexible. diaphragm isI forcedthrough conduit 51 into the com.` partment .66ct. the ice mold, as shown in 3. Rotation of ,theejectorshaft continues until at about the blades 82 contact the ice frozen in the mold 22 which eausesthe energized; ejector motor S3 to` stall. The heat ingliquidin the moldjacket-continues to heat themold, and thereset heater v73 continues toheat the mold ther-- mostat bulb 72a. so as fto reset'the switch 115 to the posi,- tion shown; inFig.. 2,` in contact with the terminal 123. When.l the icc is. thawed loose inthe mold,l rotation of the: ejector motor continues: whether or not the mold thermostat 72 has reset.. That-.im current ows through terminalf` 11,6 if. thelmold; thermostat has not. reset and through terminals 128 and 123 ifithas., The water inlet valve 92 closes at about the 225 point of rotation of the ejector motor. i

When thef ejector blades. 82' reach the 270 rotation point, the; cam 8.8 on the ejectorl shaft 841 quickly .raises the stop. switch 85;. breakingy the. ejector motor circuit atthat point. Iii-the, mold thermostat 7.2, has reset this, does not stop: the ejector'motor since, it is getting current through terminab 123i from terminal 128 of the micro.v

switch 126., But if the: mold thermostat has noty reset, opening of thezstop switch 85 stops4 the operation, since thev ejectorrmotor has. been getting current. from terminal 116 ofthe mold.-v thermostat 72. The reset heater 731remains'. energized;y trying: toLresetl the. mold thermostat, and' if it is` successful. rotation; ofthe ejector continues; but it itl is-i not successful itil indicates. that` the mold 'thermostatv hastlost its. charge; cannot: befreset; and the system dies permanently; with the ejectonmotor deenergizedgthc sole noid` valve 57. in;thezfneliline.deencrgizedg the water valve 93, to; theicemrildr-i closed` and; the. thermostat reset heaterl 73-energized; )In thi'szwy' a. diaphragm systemvmay be used .inl the!k mold;v thermostatv with operates above atmospheric pressure.and"instigates anice ejecting cycle'on talling pressure, whilezatfthe' same time, iithe pressurey falls below normal, a subsequent ejecting cycle is prevented from being started. That is, ify the mold thermostat 72 loses its. chargean ice. release cycle will, be instigated regardless of whether or not the water inrthemold is com pletely frozen; butthe. ejector motor will rotate only to the 270 point,v whereupon the stop-` switch185 is opened, the ejector `motor deenergizedand no more water is supplied to themolduntil; the defective thermostat has heenreplaced.

Going4 hacktowherethe'stop Switch 8.5 opened; the ejector bladesare at.27f (l.,l but,thezmold thermostat-72 is reset. Rotation-continues since the ejector motor isget` tingcurrent through terminal 12,3 from terminal 128 Vof they micro switch126.- Ataboutthe 300 point Giroteltion` the stop.. switch 85. drops freeof its cam 88 and its. circuit iseithen madeor not; depending on how much'` ice is in'.y the storage receptacle-.114. Thewatcr outletA valve 93: isiopeized.- bypacam 131:0;1 theejector shaftatthe 315 point of rotation; whereupon the flexible diaphragm 101 is shifted from the position shown in Fig. 2 to that shown in Fig. 1, and the measured charge of water is forced from the measuring vessel 50 through conduit 7S to the mold. As the flexible diaphragm 101 shifts from the position shown in Fig. 2 to that shown in Fig. 1, the heating fluid contained in the compartment 66 of the ice mold is returned by gravity through conduit 51 to the measuring vessel 50; wherein this fluid is heated by the rectifier during the next freezing cycle of the ice maker. Having mademsure that the ejector motor S3 is getting current from terminals 128 and 123, so at the 360 point of rotation the micro switch 126 snaps away from terminal 12S to terminal 127, deenergizing the ejector motor, and the rest heater and bringing the ejector blades back to the starting point with the batch of ice resting thereupon to be dried during the next freezing cycle and with 'the solenoid valve 57 in the fuel line energized. The water outlet valve remains open during the freezing cycle and is closed at the 45 point of rotation of the ejector motor on the next release cycle.

The absorption type refrigerating system illustrated and described above may be replaced by a compression type system. In which case, the measuring vessel 50, shown in Figs. l and 2, or 50' shown in Fig. 5, is placed in heat exchange relation with the condenser or other heat dissipating part of such system. Also, when a compression system is used, the compressor motor of such system replaces and is located in the same position in the electric circuit as the solenoid operated valve 57 in Fig. 2, and the generator, the gas burner and the fuel gas line are eliminated. Otherwise the wiring diagram and the controls are the same for a compression system as that shown in Fig. 2 for an absorption refrigerating system. In either case, when the heating fluid is in the compartment 66 of the ice mold, thawing the ice pieces free of the mold, and the micro switch 126 is in contact with the terminal 128, the refrigerating system stands idle and no refrigerant fluid is supplied to the evaporator coil 13b. With this arrangement the heating fluid is not opposed by refrigerating fluid.

Without further description, it is thought that the features and advantages of the invention will be readily apparent to those skilled in the art to which this invention appertains, and it will, of course, be understood that changes in form, proportions and minor details of construction may be resorted to without departing from the spirit of the invention and scope of the claims.

What is claimed is:

1. An ice mold having an ice forming compartment therein, means for supplying a measured quantity of water to the interior of said compartment to be frozen therein, means for supplying cooling medium to the exterior of said compartment to freeze said Water, and means for supplying a measured quantity of heating medium to the exterior of said compartment to free the ice from the interior thereof, said water supply means, said cooling medium supply means and said heating medium supply means being interconnected in a manner that the freezing of Water in the compartment energizes the heating medium supply means and deenergizes the cooling medium supply means, and the supplying of a measured quantity of water to the interior of the compartment causes withdrawal of a measured quantity of heating medium from the exterior of the compartment.

2. In an automatic ice maker, an ice mold, means for supplying water to said mold to be frozen therein, refrigeratng means for freezing the water in said mold, and means for thawing the ice free of the mold, said water supply means and said thawing means including a measuring vessel divided into a water compartment and a heating fluid compartment, and means operable responsive to the freezing of ice in said mold for alternately operating said ice thawing and said mold filling means.

3. An automatic ice maker as set forth in claim 2 wherein heating lluid is supplied to said ice mold responsive to the supply of water to said measuring vessel.

4. An automatic ice maker as set forth in claim 2 wherein heating fluid is withdrawn from said mold responsive to the supply of water thereto from said measuring vessel.

5. An automatic ice maker as set forth in claim 2 wherein said measuring vessel is provided with an inlet and an outlet valve and wherein said valves are operated in sequence in a manner as to first supply water to the measuring vessel and heating fluid from the measuring vessel to the mold and second to supply water from the measuring vessel to the mold and heating fluid from the mold to the measuring vessel.

6. An automatic ice maker as set forth in claim 2 wherein said refrigerating means includes a refrigerating system having a heat absorbing part and a heat dissipating part, and wherein said ice mold is in thermal contact with saidheat absorbing part and said measuring vessel is in thermal contact with said heat dissipating part.

7. An automatic `ice maker as set forth in claim 2 wherein said refrigerating means includes an absorption type refrigerating system having a generator, a rectifier, a condenser, an evaporator and an absorber, and wherein said ice mold is placed in thermal contact with said evaporator and said measuring vessel is placed in thermal contact with said rectifier.

8. In an automatic ice maker, a heat exchange element, means for supplying water to said element to be frozen thereon, a refrigerating system for freezing water on said element, and means for supplying a heating medium to said element for thawing ice therefrom, said water supply means including a cylinder divided by a piston into a water chamber and a heating fluid chamber, and said pist0n being movable in one direction to force heating medium therefrom to said heat exchange element and in an opposite direction to force water therefrom to said heat exchange element.

9. An automatic ice maker as set forth in claim S which includes means for removing ice from proximity of said heat exchange element and which means is operated by said water supply means.

10. An automatic ice maker as set forth in claim S wherein said heating fluid chamber is placed in thermal contact with a heat rejecting part of said refrigerating system to be heated thereby.

11. An automatic ice maker as set forth in claim 8 wherein said water supply means includes valve mechanism operable in one position to admit water to said cylinder and force heating medium therefrom to said heat exchange element, and operable in a second position to force water from said cylinder to said heat exchange element and to admit heating fluid to said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,868,503 Kennedy July 26, 1932 2,026,227 Foraker Dec. 3l, 1935 2,221,212 Wussow Nov. 12, 1940 2,221,694 Potter Nov. l2, 1940 2,407,058 Clum Sept. 3, 1946 2,421,293 Shawhan May 27, 1947 2,443,203 Smith lune l5, 1948 2,549,747 Leeson Apr. 17, 1951 2,569,113 Munshower Sept. 25, 1951 2,631,442 Melcher Mar. 17, 1953 

